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Thread: Bonding an AGP - what am I protecting against?

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    Bonding an AGP - what am I protecting against?

    Hi All,

    I've read many threads about 'how' to perform the bonding on an above ground pool. Other than a few differences of opinion on using a grounding rod and bonding the water, I understand what to do. My question is what does the bonding actually do in regards to safety? I understand that it has nothing to do with the grounding of my pump as that is totally separate. But I just don't understand what I'm protecting against.

    Thanks,
    CJ

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    JasonLion's Avatar
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    Re: Bonding an AGP - what am I protecting against?

    Welcome to TFP!

    You are protecting people in the pool from getting electrocuted. By connecting everything together electrically the bonding system makes sure any current present flows through the bonding system instead of flowing through the people.
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    Re: Bonding an AGP - what am I protecting against?

    Thanks Jason,

    That's the part I'm not understanding. I thought that by 'grounding' my motor and making sure that its on a GFCI that I'm protecting against electrocution in the event that the motor fails somehow.

    Quote Originally Posted by JasonLion View Post
    Welcome to TFP!

    You are protecting people in the pool from getting electrocuted. By connecting everything together electrically the bonding system makes sure any current present flows through the bonding system instead of flowing through the people.

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    Re: Bonding an AGP - what am I protecting against?

    Quote Originally Posted by catalano View Post
    Thanks Jason,

    That's the part I'm not understanding. I thought that by 'grounding' my motor and making sure that its on a GFCI that I'm protecting against electrocution in the event that the motor fails somehow.
    What if an extension cord gets dropped in the pool? What if a construction crew touches a power line next door with a steel excavator and your yard is connected to 12,000V? The bonding protects you from any electrical source, not just the power to your equipment.
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    Re: Bonding an AGP - what am I protecting against?

    Catalans, thank you for asking this question. I've wondered the same thing.

    Jason, John, thank you too for the explaination. When I set up my intex I'd read about bonding but the electrician nor the city inspector said anything about it. Y'all now have me thinking. Ouch.
    Angie M.
    AG, 26' x 52" Intex Ultra Frame, vinyl, 14667 gal. And LOVING it!!! Hayward S15922S 1HP, 2SP pump and Hayward S220T Sand Filter. Hard plumbed with PVC, added second return, intex SWG, Hydro Pool widemouth skimmer. Set up in May 2012!
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    Re: Bonding an AGP - what am I protecting against?

    Ok, I think I'm beginning to understand. So in the case of an extension cord being dropped in the pool, the bonding grid will serve as the ground for the cord whereas if the pool wasn't bonded then if someone was stepping out of the water, or someone on the outside was reaching into the water, that person would serve as the ground path and be electrocuted. Is that right?

    In the case of the excavator I'm not so sure I understand. I'm guessing that you're protecting from someone standing on the ground and touching the water and becoming the path for the electricity from the energized yard into the pool. But would the electricity want to flow into the pool? It wouldn't have anywhere to go from there. Isn't the path of least resistance already the yard?

    Thanks,
    CJ

    Quote Originally Posted by JohnT View Post
    What if an extension cord gets dropped in the pool? What if a construction crew touches a power line next door with a steel excavator and your yard is connected to 12,000V? The bonding protects you from any electrical source, not just the power to your equipment.

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    JasonLion's Avatar
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    Re: Bonding an AGP - what am I protecting against?

    Electricity is happy to travel through the pool. There are always places for it to connect to via the water, the pump if nowhere else. Water and people are both more conductive than soil, so it will tend to want to go through people if it can find a way to do so. Bonding connects everything a person could possibly be in contact with together so they are all at the same potential, that way no current will flow through the people.
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    Re: Bonding an AGP - what am I protecting against?

    The first thing to remember when dealing with shock hazards is that you need to contact two points that have a voltage difference between them to be in danger. Voltage difference is what causes current flow, and current flow is what is dangerous.

    If you touch the hot lead on an electrical cord while you are insulated from ground or any other conductive object, you will not be shocked. You can touch two hot leads from the same source, one in your hand and the other with your tongue (don't try this at home) and you won't be shocked because they are both at the same voltage.

    As a greatly simplified thought model, imagine that all possible electrical sources that could contact your pool are represented by a simple extension cord with bare wires on the end. The hot hanging into the pool, and the ground connected to a ground rod. The cord isn't plugged in, so it isn't doing anything, but an accident could happen and it could get plugged in causing current to flow through the pool and/or equipment.

    If the hot is in the water and the cord is plugged in, the water will rise to 120VAC, and any swimmers will too. But voltages are all relative. We may be at 5,000,000V compared to the surface of Saturn, but as long as we don't touch the surface of Saturn, nothing will happen. That 120VAC is only important relative to the neutral and ground of the same electrical system. Ground is just as dangerous to touch when you are at 120V as 120V is when you are at ground potential.

    What about the pool walls of a metal pool? They are sitting on the ground, so they are at zero volts relative to the pool water because the liner insulates them from the water. If a swimmer touches the metal wall, current will flow between their hand and the pool water. Same thing if somebody is getting ready to clean the pool. They walk up and lean against the pool wall at zero volts, and then touch the pool water with a hand or a metal pole. Current flows.

    The source of power may have a GFCI, but how do you know? It could be your crazy neighbor who ran an extension cord into his trees for mood lighting, or a previous owner of the home who didn't wire your outlets right. How can you protect against such things that you can't control or predict? The easy way is to connect everything conductive that you can touch from the pool together with a wire. If every conductive object a swimmer can touch is at the same voltage or very close, very little current will flow and the swimmers or pool cleaner will be safe.

    Bonding is the process of connecting everything conductive that a swimmer might touch from the pool together with a wire so that no two places the swimmer can touch are at different voltages.
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    Re: Bonding an AGP - what am I protecting against?

    Thank you for the explanation. This was something I didn't understand either.
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    Re: Bonding an AGP - what am I protecting against?

    Is this something that can be added after an AGP is already up??
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    Re: Bonding an AGP - what am I protecting against?

    Quote Originally Posted by Discobrian24 View Post
    Is this something that can be added after an AGP is already up??
    Yes, it can be added.
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